In the field of motor vehicle batteries, it is desirable to protect the battery from the extremes in temperature produced by the engine and the exhaust emission control apparatus. It is well known that excessively high temperatures have a decided detrimental effect on the motor vehicle battery's operating life. While some thermal protection may be afforded by shielding the battery from the heat producing sources in the engine compartment through the use of panel-type enclosures, it is also necessary to ensure that the battery receives proper ventilation in order to exhaust the corrosive acid fumes and heat produced by the battery itself.
Japanese patent abstract 1-47640 discloses a cooling arrangement for a motor vehicle battery wherein the battery is positioned immediately behind one of the motor vehicle headlights and is partitioned from the engine by use of several partition boards which form a box-like enclosure for the battery. The battery enclosure includes a front panel which is in air communication with a cutout in the headlight and an air outlet port disposed in the rear panel portion thereof adjacent the front wheel housing. In operation, when the vehicle is moving, the battery compartment is ventilated by cool air entering through the headlight opening. Hot air within the enclosure is exhausted through the air outlet port and eventually exits to the wheel housing. In this fashion, the battery remains cool and is basically unaffected by the engine heat during driving operation. However, when the vehicle is stationary, the air circulation through the battery enclosure is not sufficient to provide adequate cooling.
In order to improve the air circulation through a battery enclosure when the vehicle is stationary, it has been proposed to position the battery within a first housing which, in turn, is received within a second outer battery enclosure. The outer enclosure is provided with a ventilation opening and an evacuation channel. The evacuation channel is preferably sloped upwards in order to create a chimney effect so that hot air is caused to be carried away from the battery and fresh air is caused to be sucked into the enclosure through the ventilation opening. In practice, however, it has been found that sufficient cooling for the battery cannot be achieved in this way.
From U.S. Pat. No. 2,104,765 issued to Saunders, it is known to provide a battery enclosure having an air inlet port and air outlet port with a false bottom and sides for supporting the battery a distance away from the walls of the battery enclosure. In this arrangement, a flue is created which permits air flow across diagonally opposite top and bottom corners of the enclosure. Saunders also discloses an air inlet port with a connecting inlet tube having a belled mouth positioned near the fan such that positive air induction to the enclosure is provided by the fan blast. In this arrangement, the belled mouth of the air inlet tube is located behind the fan which, in turn, is located behind the radiator. Thus so positioned, the air inlet tube is blocked by the radiator from receiving pressurized air flow which enters the forward portion of the engine compartment when the vehicle is moving. This requires that the fan to be operated at all times to ensure adequate cooling air flow to the battery. In many modern day vehicles, operation of the cooling fan for the radiator is temperature dependent whereby fan activation occurs when the engine temperature exceeds a preselected threshold level such as when it is very hot outside or when the vehicle is stationary or moving slowly.
Accordingly, there is a need in the art for a simple low cost arrangement for cooling a battery of a motor vehicle which provides sufficient flow of cooling air across the battery irrespective of whether the motor vehicle is moving or is stationary. There is also a need for such a battery cooling arrangement which does not require additional power means for providing cooling air flow to the battery while the motor vehicle is stationary.